Anode for a magnetron having deverse size cavity resonators



H. PICK Dec. 20, 1966 A.

v ANODE FOR A MAGNETRO SIZE CAVITY R ERING 3,293,487 N HAVING DEVERSEESONA'IORS 2 Shegts-Sheet 1 Filed July 25, 1962 PRIOR ART F/GZ.

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\NVENTOR Wad/A BY ATTORNE lNG 3,293,487 HAVING ,DEVERSE ESONATORS Dec.20, 1966 A. H. PICKER ANODE FOR A MAGNETRON SIZE CAVITY R Filed July 25,1962 2 Sheets-Sheet 2 lNvENroR MM 1 BY ATTORNEY United States Patent3,293,487 ANODE FOR A MAGNETRON HAVING DEVERSE SIZE CAVITY RESONATORSAlan Hugh Pickering, Springfield, Chelmsford, England, assignor toEnglish Electric Valve Company Limited, London, England, a company ofGreat Britain Filed July 25, 1962, Ser. No. 212,313 Claims priority,application Great Britain, Oct. 4, 1961, 35,751/ 61 14 Claims. (Cl.SIS-39.65)

This invention relates to cavity magnetrons and more specifically t-ocavity magnetrons of the Well-known socalled rising sun type, i.e. thetype in which the anode system is provided with radial slot cavities,adjacent ones of which are of different radial lengths. The objects ofthe invention are to provide improved inexpensive rising sun magnetronsthe anode systems of which can be made by manufacturing methods whichare substantially more economical and easier to practise than thoseusually employed at the present time and to provide improved and simplemeans for manufacturing such anode systems.

The invention is illustrated in and explained in connection with theaccompanying drawings, in which: FIGURE 1, which is provided forpurposes of explanation, is a sectional view of part of the anode systemof a conventional known rising sun magnetron; and the remaining FIGURES2 to 11 illustrate mangetron anode systems in accordance with thepresent invention and processes for manufacturing the same.

FIGURE 1 shows part of the anode system of a conventional present-dayrising sun magnetron. It consists of a carcase C, usually of copper, inwhich are formed radial slot cavities S1, S2 of one or other of twodifferent radial lengths, the shorter cavities S1 alternating with thelonger cavities S2 round the carcase. The present-day normal method offorming the cavities is either by hobbing or by spark machining. Bothare expensive and both involve the manufacture of costly tools of highaccuracy since the sizes and shapes of the tools determine the sizes andshapes of the cavities. In manufacture by hobbing the tools have to bemade of good quality steel Which will withstand the considerable forcesinvolved when pushed into hot copper. Such tools are of limited life andnot readily altered, e.g. to enable a tool designed and made to form acavity of given dimensions to be used if the magnetron frequency is tobe changed requiring the formation of a cavity of different dimensions.In manufacture by spark machining the tools are, of course, notsubjected to mechanical stresses when in use but they are subjected tovery considerable erosion and have, accordingly, very limited life.Tools of the latter type must be replaced after a relatively short timeof use if the normal requirement of accurate dimensioning of thecavities is to be satisfied.

The present invention seeks to avoid these defects and to provide risingsun magnetrons anode system of which can be made to high standards ofaccuracy by methods which are cheaper, easier and more flexible than theabove described present day methods, which use tools which are cheaperand last longer than the tools employed in the said present day methodsand which are such that the same tOOls can be used to maufacture anodesystems of widely different dimensions.

According to this invention a rising sun magnetron includes an anodesystem consisting of a metal carcase member, a plurality of separatemetal vane members which are fixed to said carcase member so as toproject radially inward therefrom at equal angular intervals round thecarcase and a plurality of separate metal intermediate members which arealso in fixed positions in relation to said carcase member and projectradially inward therefrom but "ice which are of substantially shorterradial length than the vane members so as to project inward for asubstantially shorter distance, each intermediate member occupying partof the space between two different adjacent vane members, certainadjacent vane members having an intermediate member between them andother adjacent vane members being without anintermediate member betweenthem.

If, as is normally the case, the rising sun anode system is one in whichlong and short slot cavities are required to occur alternately round thecarcase, there is an even number of vane members and half that number ofintermediate members so positioned that these are two vane membersbetween each two successive intermediate members round the carcase.

Preferably each vane member is parallel sided and each intermediatemember is tapered in such manner that when the vane and intermediatemembers are in position the side faces of each intermediate member areparallel to the side faces of the vane members between which it islocated. Preferably also the arcuate extent of each intermediate memberover at least the major part of its radial length is less than thearcuate extent of each space between adjacent vane members so as toleave a small similar space on each side of each intermediate memberbetween the side faces thereof and the side faces of the adjacent vanemembers.

Preferably again the vane members are fitted at their outer ends intoand fixed in relatively shallow radial vanereceiving slots formed in thecarcase.

The intermediate members may be solid or hollow and may be fixed bybrazing or the like to the carcase or may "be fitted at their outer endsinto and fixed in relatively shallow intermediate member-receiving slotsformed in the carcase. Where hollow intermediate members are employedthey are preferably bent up from sheet metal into approximately taperedU form and the ends of each U-shaped intermediate member are fitted intoand fixed in two receiving slots formed in the carcase. Alternativelythe ends of each U-shaped intermediate member may be splayed out andfixed by brazing or the like to the vanes on either side thereof nearthe carcase. Where solid intermediate members are employed they arepreferably made from a hollow metal tube of thickness equal to therequired radial length of intermediate member by slotting said tuberadially. Alternatively they can be made by extrusion. The vane membersare preferably made by cutting or stamping them from precision rolledsheet. Where, as is much, preferred, the vane members are fixed in vanereceiving slots in the carcase the same vane members may be used foranode systems of different amounts of vane projection and therefore ofdifferent frequencies or circuit ratios without change to the broachingtool which cuts the vane-receiving slots in the carcase, by simplyaltering the inner diameter to which the carcase is bored outa verysimple matter since the boring of the carcase can be done on an ordinarycentre-lathe.

FIGURES 2 to 4 illustrate one construction of anode system for a risingsun magnetron in accordance with this invention.

Referring to FIGURE 4 the cylindrical copper carcase or shell C is cutwith a number of equally spaced relatively shallow slots C1 in anyconvenient manner, e.g. by an ordinary breach or slotting machine. Theseslots which are to receive the vane members are of a depth chosen togive whatever range of selectable vane member radial projection isrequired. Parallel sided vane members V (FIGURE 4) are cut or stampedfrom precision rolled sheet copper and are inserted into the slots tothe required depth. They are a good fit in the slots and are preferablybrazed in position though they may be fixed in other ways. Taperedintermediate members F are preferably made from a cylinder tube T byslotting the same as indicated in FIGURE 3. Each intermediate member isfixed by brazing to the inside surface of the carcase C between two ofthe vane members, there being two vane members between the intermediatemembers of each successive pair round the carcase. Thus, as shown inFIGURE 4, there is first a short cavity, i.e. one with an intermediatemember in it between two vane members; then a long cavity, i.e. onewithout an intermediate member in it between two vane members; then ashort cavity and so on with long and short cavities alternating roundthe anode system. In this way the required alternate long and shortcavities are formed. As will be seen from FIGURE 4, the arcuate extentof each intermediate member is less than that of the intervane gap inwhich it is situated so that small similar gaps are left between theside faces of each intermediate member and the adjacent side faces ofthe vane members between which it is situated. This gap is importantinasmuch as its provision ensures that there will be no risk of the vanemembers being forced out of their correct positions when brazing orsoldering takes place. Of course the brazing or soldering of the partsis effected when the said parts are assembled and held in their correctrelative positions by a suitable jig (not shown).

Instead of making the intermediate members by cutting them from acylinder as shown in FIGURE 3, they may be extruded.

FIGURES 5, 6 and 7 show a modification in which intermediate members,assumed to be extruded and one of which is shown at F in FIGURE 6, arefitted into and fixed in additional shallow slots C2 cut in the carcase.The intermediate members are fitted in the slots C2 and brazed orotherwise fixed there.

FIGURES 8, 9 and 10 show a further modified construction in which theintermediate members are hollow instead of solid and are made by bendingup sheet copper into an approximately tapered U form. Such anintermediate member is shown in section at F in FIGURE 8. As shown inFIGURE 9, the carcase C is provided with pairs of slots C3 for receivingthe ends of the bentup U-shaped hollow intermediate members, theresulting assembled construction being best shown in FIGURE 10.

FIGURE 11, which is a view like that of FIGURE 2, shows a minormodification of the embodiment of FIG- URES 8, 9 and 10. Here again theintermediate members, referenced F, are hollow and made by bending upsheet copper into approximate U form. However, the ends of the limbs ofthe U, instead of being fixed in slots (C3 in FIGURE 9) which areprovided in the carcase for receiving said ends, are splayed outwardlyand fixed, for example by welding, to the adjacent vane members andadjacent the inner wall of the carcase. In this way a good deal of notinexpensive carcase slotting is eliminated.

With all these constructions there is a substantial range of inwardradial projection of the vane members V available by selecting the depthof penetration of those members in their receiving slots C1. Ifvariation of the inward radial projection of the intermediate members Fof F is required, it is contemplated to effect this by making theintermediate members of different lengths but, owing to the method ofmanufacture, this is a comparatively cheap and simple matter to do.

It will be seen that the invention lends itself to the ready andeconomical manufacture of rising sun magnetron anode systems of highprecision. The tools employed are reasonably inexpensive and ofreasonably long life. Furthermore the way in which they are employed issuch that it is not necessary to make new sets of special and expensivetools for each. differently dimensioned magnetron to be manufactured.

I claim:

1. A rising sun. magnetron including an anode system comprising a m l crwse member, a. plurality of separate metal vane members which are fixedto said carcase member so as to project radially inward therefrom atequal angular intervals pound the carcase member, and a plurality ofseparate metal intermediate members which are also in fixed positionsin. relation to said carcase member and project radially inwardtherefrom but which are of substantially shorter radial length than thevane members so as to project inwardly for a substantially shorterdistance, each intermediate member occupying part of the space betweentwo different adjacent vane members, certain adjacent vane membershaving an intermediate member between them and other adjacent vanemembers being VVilhOllt an intermediate member between them.

2. A magnetron as claimed in claim 1 wherein the rising sun anode systemis one in which long and short cavities occur alternately round thecarcase and there is an even number of vane members and half that numberof intermediate members so positioned that there are two van membersbetween each two successive intermediate members round the carcase.

3. A magnetron as claimed in claim 1 wherein each vane member isparallel sided and each intermediate member is tapered in such mannerthat when the vane members and intermediate members are in position theside faces of each intermediate member are parallel to the side faces ofthe vane members between which it is located.

4. A magnetron as claimed in claim 1 wherein the arcuate extent of eachintermediate member overat least the major part of its radial length isless than the arcuate extent of each space between adjacent vane membersso as to leave a small similar space on each side of each intermediatemember between the side faces thereof and the side faces of the adjacentvane members.

5. A magnetron as claimed in claim 1 wherein the vane members are fittedat their outer ends into and fixed in relatively shallow radialvane-receiving slots formed in the carcase.

6. A magnetron as claimed in claim 1 wherein the intermediate membersare solid.

7. A magnetron as claimed in claim 1 wherein the intermediate membersare hollow.

8. A magnetron as claimed in claim 1, the intermediate members beingbrazed to the carcase.

9. A magnetron as claimed in claim 1, the intermediate members beingfitted at their outer ends into and fixed in relatively shallowintermediate member-receiving slots formed in the carcase.

10. A magnetron as claimed in claim 7 wherein the intermediate membersare bent up from sheet metal into approximately tapered U form.

11. A magnetron as claimed in claim 10 wherein the ends of each U-shapedintermediate member are fitted into and fixed in two receiving slotsformed in the carcase.

12. A magnetron as claimed in claim 10 wherein the ends of each U-shapedintermediate members are splayed out and fixed by brazing to the vaneson either side thereof near the carcase.

13. A magnetron as claimed in claim 6 and having intermediate membersmade from a hollow metal tube of thickness equal to the required radiallength of intermediate member by slotting said tube radially.

14. A rising sun magnetron including an anode system comprising a metalcarcase member, a plurality of metal vane members constructed separatelyfrom said carcase member and fixed thereto so as to project radiallyinward therefrom at equal angular intervals round the carcase member,and .a plurality of metal intermediate members constructed separatelyfrom said carcase member which are also in fixed positions in relationthereto and project radially inward therefrom but which are ofsubstantially shorter radial length than the vane members so as toproject inward for a substantially shorter distance, each intermediatemember occupying part of the space between two different adjacent vanemembers, certain adjacent vane members having an intermediate memberbetween them thereby forming the short resonant cavities of the risingsun magnetron and other adjacent vane members being without anintermediate member between them thereby forming the long resonantca'vities of the magnetron.

6 References Cited by the Examiner UNITED STATES PATENTS 2,655,61610/1953 Rollin 31539.65 X 2,828,441 3/1958 Jenny 315-3917 X HERMAN KARLSAALB ACH, Primary Examiner.

ARTHUR GAUSS, Examiner.

S. CHATMON, JR., Assistant Examiner.

1. A RISING SUN MAGNETRON INCLUDING AN ANODE SYSTEM COMPRISING A METALCARCASE MEMBER, A PLURALITY OF SEPARATE METAL VANE MEMBERS WHICH AREFIXED TO SAID CARCASE MEMBER SO AS TO PROJECT RADIALLY INWARD THEREFROMAT EQUAL ANGULAR INTERVALS ROUND THE CARCASE MEMBER, AND A PLURALITY OFSEPARATE METAL INTERMEDIATE MEMBERS WHICH ARE ALSO IN FIXED POSITIONS INRELATION TO SAID CARCASE MEMBER AND PROJECT RADIALLY INWARD THEREFROMBUT WHICH ARE OF SUBSTANTIALLY SHORTER RADIAL LENGTH THAN THE VANEMEMBERS SO AS TO PROJECT INWARDLY FOR A SUBSTANTIALLY SHORTER DISTANCE,EACH INTERMEDIATE MEMBER OCCUPYING PART OF THE SPACE BETWEEN TWODIFFERENT ADJACENT VANE MEMBERS, CERTAIN ADJACENT VANE MEMBERS HAVING ANINTERMEDIATE MEMBER BETWEEN THEM AND OTHER ADJACENT VANE MEMBERS BEINGWITHOUT AN INTERMEDIATE MEMBER BETWEEN THEM.